As is known, the rubber compounds used to make tyre parts comprise anti-aging agents to prevent deterioration of the rubber caused by the polymer base reacting with oxygen and/or ozone.
Anti-aging agents are materials added to compounds susceptible to oxidation, such as rubber, to prevent or slow down oxidation processes (by themselves becoming oxidized). In other words, anti-aging agents are materials capable of reacting with atmospheric agents and so preventing the latter from reacting with the polymer base.
The anti-aging agent concentration in the compound depends on the degree of exposure to the atmosphere, and on the temperature and mechanical stress conditions to which the tyre part made from the compound is subjected.
The most commonly used anti-aging agents form part of the paraphenylenediamine (PPD) family, such as N-1,3-dimethylbutyl-N′-phenyl-paraphenylenediamine (6PPD) and N,N′-diphenyl-p-phenylenediamine (DPPD), or may be phenol derivatives, such as 2,6-di-tert-butyl-4-methylphenol (BHT), or form part of the vitamin E family, such as α-tocopherol, α-tocotrienol, γ-tocopherol and γ-tocotrienol, or the quinoline family, such as poly(1,2-dihydro-2,2,4-trimethylquinoline) (TMQ).
Research by the Applicant has uncovered a new class of anti-aging agents which, in polymer compounds, and particularly rubber compounds, may be used as a valid alternative to known anti-aging agents.